Strip Profile Research Articles

A Comprehensive Model to Compute Roll Gap Profile for a Rolling Mill Including Bearing and Mill Housing Deflections

Abstract Obtaining the desired strip profile is of paramount importance in cold rolling. The final strip profile depends on several parameters of the plants including crown and taper profiles and segmented backup roll positions. This paper aims to present a newly developed combined finite element–analytical model of the rolling mill able to model not only the roll cluster but also the mill housing and backup bearings deformations. This makes the proposed model especially suitable to simulate cluster-type rolling mills. The model exploits a modified elastic foundation formulation for a precise computation of the contact forces between rolls, taking into account rolls’ crown and taper. A reduced stiffness matrix approach is implemented for accurate mill housing modeling. A full 3D finite element model of the rolling mill and experimental data are used for the validation of the presented model. By exploiting the validated model, the paper shows that the deformation of supporting bearings and mill housing plays a crucial role in the strip profile calculation and should be included in any cluster-type roll mill model.

Prediction and control of profile for silicon steel strip in the whole tandem cold rolling based on PSO-BP algorithm

In the rolling process of silicon steel strip of the five-stand UCMW tandem cold rolling line, the quality of finished profile is the result of cooperative control of five stands, the exit profiles of the first four stands jointly decide the exit profile of the fifth stand, so it is necessary to accurately control the strip profile in the rolling process. However, the shapemeter is only typically equipped at the exit of fifth stand, making it impossible to obtain the strip profile of the first four stands. A profile prediction model for the whole tandem cold rolling based on PSO-BP algorithm is established, compared with the finite element method, this model can satisfy the demand for fast prediction of strip profile and quickly analyzing the profile change characteristics for five stands according to the adjustment of profile control parameters in the industrial field. Firstly, a 3D elastic-plastic finite element model of rolls and strip for five stands is built, and a large number of profile calculation data are as the training sample sets to build the PSO-BP model. Through the transfer calculation of strip profile between adjacent stands, the PSO-BP model of five stands is established, and the validity is verified by comparing with the actual measured data. Secondly, to improve the quality of product profile, focusing on the unreasonable setting of production parameters, many improvement schemes of WRB and WRS for five stands are designed, and the PSO-BP model is used to quickly calculate the strip profile, then comparing the result of each scheme, the optimum improvement scheme is selected, which is furtherly carried out rolling experiments in the industrial field, and the quality of strip profile is well improved. At present, the new scheme has been successfully applied to industrial production.

Analysis of Edge Drop on Strip Due to Bending and Elastic Deformation of Back up Rolls in a Four-High Cold Mill

The superficial quality of the strip is a very important issue in steel production. Considering the dimensions, the thickness is one of the most important variables in the production of a strip. In the present study, the elastic curve of Back Up Rolls (BURs) is analyzed, considering them as simply supported beams as well as the effect of rolls on the profile of the strip, specifically in the strip edge producing edge drop. The analysis included theoretical and numerical measurements in the mill. The results showed that there is an instability zone of 76 mm in the strip edge, and this geometry is symmetrical in both ends of the strip. This study not only provides a theoretical basis for the edge drop, but also provides a basis for the understanding of deformation on rolls used in rolling mill processes and their effect on the thickness, profile, shape, and dimensional quality of strips. To reduce the edge drop and significantly improve the surface quality of the strip, it is suggested to complement the simulation by compensating for the elastic curve of BUR, in the process applying bending on Work Roll (WR) combined with the use of positive crowns on it.

Effect of cube texture on local softening of friction stir welded joints for nanostructured AA2024 processed by accumulative roll bonding

The current research provides an insight into the correlation between the crystallographic textures, microstructure, and hardness of friction stir welded joints in nanostructured AA2024 alloys processed through accumulative roll bonding (ARB). Utilizing varying rotational speeds (250, 500, 750, and 1000 rpm) at a constant traverse tool (150 mm/min) during friction stir welding (FSW), microstructural analyses reveal distinct grain structures and texture components in the nugget zone. The fully recrystallized Cube {001}⟨100⟩ texture-oriented grains appear at the rotational speed of 750 rpm. The hardness profiles of ARB-processed strips after FSW at different rotational speeds show local softening in the nugget zones. There might be a hypothesis concerning the dissolution of stable and metastable precipitates based on generated heat input, providing insights into the mechanisms influencing hardness variations. Notably, the examination of Cube {001}⟨100⟩ texture and its correlation with local softening adds a valuable dimension to the understanding of microstructural changes in FSW of nanostructured AA2024 alloys processed by accumulative roll bonding process.

Pultrusion of thermoplastic composites with mechanical properties comparable to industrial thermoset profiles

Pultruded thermoplastic composite profiles offer several advantages over their conventional thermoset counterparts, such as high impact toughness, recyclability, and smaller environmental footprint. However, thermoset profiles outperform thermoplastic composite profiles in terms of mechanical properties through high fiber volume fraction. The study is aimed at producing thermoplastic profiles with high content of reinforcing fibers, using preconsolidated tapes manufactured in-house from glass fiber/polypropylene commingled yarns with fiber content of 80 % by weight. The tapes were manufactured with the use of extrusion machine at speeds of 2, 5, and 8 m/min under the same temperature conditions. The strip profiles of 75 mm × 3.5 mm with fiber volume fraction of 50 % were produced of 76 tapes by thermoplastic pultrusion process at the pulling speed of 0.2 m/min. The results of mechanical tests show that flexural strength and modulus of obtained thermoplastic profiles exceed minimal requirements to industrial thermoset profiles, constituting at least 488 MPa and 37 GPa respectively. Thermoplastic profile pultrusion from tapes made of commingled yarns does not require the use of a preheating chamber, produces profiles with 1 % porosity, and more energy efficient pultrusion process than pultrusion from commingled yarns.

A defect recognition model for cross-section profile of hot-rolled strip based on deep learning

A defect recognition model for cross-section profile of hot-rolled strip based on deep learning

A ROLL’S WEAR DURING HOT ROLLING OF HIGH-SILICONSTEEL AND ITS IMPACT ON THE QUALITY OF A STRIP’SPROFILE

Hot rolling of grain-oriented high silicon steel is related to technical problems such as high temperature andlong rolling campaigns with strips of the same width. Numerous methods may be carried out as a solutionto these problems. Before the rolling campaign, all rolls of finishing stands are exchanged. The campaign isscheduled with additional exchanges of rolls on two last stands in two stages. A roll’s wear increases with thequantity of rolled material and may lead to strip profile deformation. Exchanging the rolls ensures the requiredsteel quality and prevents losses caused by quality defects. This work identifies factors affecting the workroll's wear and refers to the material from which rolls are made. This work aimed to determine the wear ofwork rolls of the finishing group rolling mills during the rolling of high-silicon steel. The work presents wearanalyses of 30 rolls. It was analysed depending on roll type and high silicon steel rolled material quantity.Compared wear of rolls after rolling high-silicon steel and black sheet. By analysing the distribution of rollwear along the length of the roll, it was found that the wear of working rolls directly affects the geometry ofthe rolled sheet, which may affect the quality of the strip profile of the rolled sheet.

Research on the generation and control of high-order flatness during the controlling of titanium strip profile by the intermediate taper roll in a 20-high mill

Research on the generation and control of high-order flatness during the controlling of titanium strip profile by the intermediate taper roll in a 20-high mill

Effects of Additives on the Mechanical and Fire Resistance Properties of Pultruded Composites.

Under high temperatures, fiber-reinforced polymers are destroyed, releasing heat, smoke, and harmful volatile substances. Therefore, composite structural elements must have sufficient fire resistance to meet the requirements established by building codes and regulations. Fire resistance of composite materials can be improved by using mineral fillers as flame-retardant additives in resin compositions. This article analyzes the effect of fire-retardant additives on mechanical properties and fire behavior of pultruded composite profiles. Five resin mixtures based on vinyl ester epoxy and on brominated vinyl ester epoxy modified with alumina trihydrate and triphenyl phosphate were prepared for pultrusion of strip profiles of 150 mm × 3.5 mm. A series of tests have been conducted to determine mechanical properties (tensile, flexural, compression, and interlaminar shear) and fire behavior (ignitability, flammability, combustibility, toxicity, smoke generation, and flame spread) of composites. It was found that additives impair mechanical properties of materials, as they the take place of reinforcing fibers and reduce the volume fraction of reinforcing fibers. Profiles based on non-brominated vinyl ester epoxy have higher tensile, compressive, and flexural properties than those based on brominated vinyl ester epoxy by 7%, 30%, and 36%, respectively. Profiles based on non-brominated epoxy resin emit less smoke compared to those based on brominated epoxy resin. Brominated epoxy-based profiles have a flue gas temperature which is seven times lower compared to those based on the non-brominated epoxy. Mineral fillers retard the spread of flame over the composite material surface by as much as 4 times and reduce smoke generation by 30%.

Finite Deformation of Scleral Tissue under Electrical Stimulation: An Arbitrary Lagrangian-Eulerian Finite Element Method.

The sclera is considered as the principal load-bearing tissue within the eye. The sclera is negatively charged; thus, it exhibits mechanical response to electrical stimulation. We recently demonstrated the electroactive behavior of sclera by performing experimental measurements that captured the deformation of the tip of scleral strips subjected to electric voltage. We also numerically analyzed the electromechanical response of the tissue using a chemo-electro-mechanical model. In the pre-sent study, we extended our previous work by experimentally characterizing the deformation profile of scleral strips along their length under electrical stimulation. In addition, we improved our previous mathematical model such that it could numerically capture the large deformation of samples. For this purpose, we considered the transient variability of the fixed charge density and the coupling between mechanical and chemo-electrical phenomena. These improvements in-creased the accuracy of the computational model, resulting in a better numerical representation of experimentally measured bending angles.

Deep-learning-based localized porosity analysis for laser-sintered Al2O3 ceramic paste

We propose a deep-learning-based (DL-based) localized porosity analysis method to quantitatively map the surface porosity profile of the laser-sintered Al2O3 ceramic paste. A micro-pores detection and segmentation model was established by training the scanning electron microscopic (SEM) images of the laser-sintered Al2O3 ceramics using the Mask Region-based Convolutional Neural Network (Mask R–CNN). The obtained model was applied to automatically detect and segment the micro-pores out of the SEM images, and the surface porosity at the corresponding locations was calculated as the percentage of the pixels at the segmented pores within the SEM images. To improve the performance of the model, different training strategies were investigated to optimize the accuracy of micro-pores detection and segmentation. By comparing the AP50 values of the models trained by different strategies, the optimal model with an AP50 value of 0.894 was obtained after trained by a 101-layer residual neural network (ResNet) under supervised learning. To validate the developed models, a set of SEM images which is not used for the training processes has been applied to the surface porosity calculation. By calculating the surface porosity at the selected microscopic locations using the optimal model, the surface porosity profiles of the laser-sintered Al2O3 strips processed by different laser powers were quantitatively estimated. In addition, the surface porosity profiles calculated by the developed model were compared with the measurement results obtained from the existing image processing software to further evaluate the accuracy of the developed models.

Development of a mathematical model for predicting the transverse profile of dynamo steel cold-rolled strips. Message 1

Development of a mathematical model for predicting the transverse profile of dynamo steel cold-rolled strips. Message 1

Effects of Transversal Temperature Distribution and Phase State on Strip Profile During Hot Rolling Process

Transversal temperature distribution and phase transformation of the strip steel in hot rolling process are analyzed by thermographic observations and thermal simulation tests. The effects of transversal temperature distribution and phase state on strip profile are investigated by finite element (FE) simulations, in which the material model of the strip steel is generated from the thermal simulation tests and a constitutive model. FE calculation shows that the decreased temperature at the edge causes smaller strip crown with the dual‐phase state, while it leads to edge bulges in strip profile under single‐phase state. With the convex temperature distribution, large strip crown is witnessed under dual‐phase state; small crowns or even edge bulges appear under the single‐phase state. For the concave temperature distribution, opposite conclusions are drawn compared with the convex temperature distribution. Measures to prevent edge bulges and control the strip crown are proposed and applied to industrial production. Reheating the edge area and assigning large target crown to the former stand of the finishing mill can avoid the edge bulges. Strip crown of the steel is more significantly affected by the bending force under dual‐phase state than that under single‐phase state.

Research on Strip Profile Control Characteristics of 1500 mm Quintic CVC Mill

Compared with cubic Continuously Variable Crown (CVC), quintic CVC presents integrated control capability of quadratic and quartic crown. In order to take full advantage of quintic CVC and have better comprehensive control of the edge wave, center wave, high order wave and complex wave in practical application, it is necessary to further clarify the complicated profile control characteristics of quintic CVC. In this paper, quintic CVC technology in a 1500 mm continuous hot rolling mill production line has been taken as the research object and use finite element method to study its profile control characteristics. Through finite element simulation, an integrated model of rolls and strip was established to analyze the influence of the shifting, bending force and rolling force on strip profile with different strip widths. Both crown adjustment area and transverse stiffness are gained to study the control capability of quintic CVC. The simulation results show that the positive shifting and positive bending of CVC work roll reduce the quadratic crown and increase the quartic crown, and the controlling effect of shifting on both quadratic and quartic crown is more remarkable than that of bending. The control capability of the crown increases with the increase of strip width. That is, wider strip has a larger crown adjustment area. Meanwhile, there is a strong coupling relationship that the increase of quadratic crown can lead to the decrease of the quartic crown, which is not good for the flexible control of strip profile. With the increase of rolling force, the quadratic crown of strip increases significantly, while the quartic crown does not change obviously. Additionally, the increase of strip width significantly increases the transverse stiffness of mill.

Study on the VCRplus Back-Up Roll Contour of 1500 mm CVC Mill

The back-up rolls of hot strip mills wear considerably under the conditions of high temperature and heavy load, which affects the roll service period and the stability of strip profile control. Serious uneven wear, short service periods, and spalling problems occurred on conventional back-up rolls of upstream stand CVC mills in 1500 mm continuous hot rolling production lines. Through finite element simulations, the problems are determined to be caused by the configuration of a flat roll contour of the back-up roll and the CVC roll contour of the work roll, which leads to uneven contact pressure between the rolls. The wear distribution form is ‘anti-CVC’ shape, and there is peak contact pressure between the rolls on both sides of the roll body. In particular, the long-term negative shifting of CVC on site further increases the peak contact pressure between the rolls, resulting in uneven wear and spalling accident. Based on the design technology of VCR back-up roll contours with variable contact lengths, and considering the cooperation between the middle of the back-up roll and the CVC work roll contour, the roll contour of the back-up roll has been improved. The designed VCRplus roll contour was analyzed and evaluated by finite element simulation, including the distribution of contact pressure between rolls, the control effect of bending force, and the transverse stiffness of the roll gap. The simulation results show that the VCRplus roll contour can effectively improve the uneven distribution of contact pressure between the rolls, and effectively improve the control effect of bending force and the transverse stiffness of the roll gap. Industrial tests demonstrate that VCRplus back-up roll contours have the advantages of uniform back-up roll wear, enhanced self-sustaining of the roll contour, and further extension of the back-up roll service life. The roll contour has now stably been put into industrial production, and the rolling capacity during the back-up roll service period has been extended from 150,000,000 kg to 250,000,000 kg.

Effect of strip profile of hot-rolled silicon steel on transverse thickness difference of cold-rolled strip

ABSTRACT The cross-sectional profile of hot-rolled silicon steel strips has a great impact on the transverse thickness difference of cold-rolled strips. The genetic algorithm - Levenberg Marquardt - backpropagation neural network model was developed for the analysis of heredity effect of the cross-sectional profile of hot-rolled strip. The feature importance was analysed based on random forest and extreme gradient boosting methods. Furthermore, the influence law was analysed by data visualization. The coupling term of the strip crown and thickness , the edge drop and the coupling term of the strip wedge and thickness are recommended as key indexes of the hot-rolled silicon steel strip. As the transverse thickness difference must be controlled below 7 μm, the corresponding , , should be controlled no more than 60, between -10∼10 μm and no more than 7.5 , respectively. Meanwhile, the requirement for the cross-sectional profile indexes is synchronous.

Strip Thickness and Profile–Flatness Prediction in Tandem Hot Rolling Process Using Mechanism Model‐Guided Machine Learning

This study is focused on the multivariable, nonlinear, strong‐coupling, and time‐varying characteristics of the quality control process of hot strip rolling. Using the rolling process data from a continuously variable crown (CVC) mill of a 1580 mm hot tandem rolling line, a new prediction model of the strip thickness, profile, and flatness in hot rolling based on rolling mechanism model‐guided machine learning (ML) is developed. The weighted processing (WP) method is used to fuse the rolling mechanism and process data, to improve the relationship between the strong correlation features and the model. Combined with nondominated sorting genetic algorithm III (NSGA‐III), multiple parameters of multioutput support vector regression (M‐SVR) are optimized. The results show that the root mean square error (RMSE), mean square correlation coefficient (R 2), and mean absolute error (MAE) of the strip thickness, crown, and flatness are 2.0159, 1.3191, and 0.9355; 0.9854, 0.9895, and 0.9873; and 16.601, 1.126, and 0.604, respectively. Moreover, the established method of data fusion rolling mechanism shows strong capability to improve the model prediction accuracy, increasing it by 60%. Thus, it can offer theoretical guidance for realizing accurate control of the quality of strips and improving the quality of hot‐rolled products.

Improvement of Contact Stress Distribution Between Work Roll and Backup Roll of a Hot Strip Mill

Contact state between work roll and backup roll has significant influnce on surface fatigue and strip steel shape. In this work, the contact behaviours between work roll and backup roll of a hot strip mill were investigated. The contact stress distributions along the axial and radial direction were calculated. The effect of uneven contact stress distribution on strip steel profile was analysed. The risk of roll fatigue caused by contact stress concentration was pointed out. In order to improve the contact stress distribution, a design method of the backup roll profile was proposed. Both finite element calculation and industrial test have been carried out and showed that the new profile was excellent in reducing the peaks of the contact stress, homogenizing backup roll wear and improving strip profile.

Edge drop of GO steel strips at the hot rolling mill 2000 PJSC «NLMK»

One of the quality characteristics of hot-rolled strips is the transverse thickness variation. The transverse thickness difference is defined as the maximum difference between the measured values of the thickness of the strip in its middle, as well as at a distance of 10 to 40 mm from the edge, depending on the standard used. In many ways, the transverse thickness variation determines the manufacturability of subsequent processing, and also affects the breakage during subsequent cold rolling. Moreover, in recent years there has been a trend towards establishing additional requirements for the transverse thickness variation of electrical steel strips, which often leads to an increase in edge trim to meet these requirements; in particular, this refers to the value of the edge drop of the cross-sectional profile, which is defined as the difference in the thickness of the strip between the edge of the strip and 40 mm from the edge. It is known that the contour of the cross-sectional profile of a hot-rolled strip is inherited by a cold-rolled strip, while the value of the transverse thickness difference decreases in proportion to the elongation coefficient. Thus, hot rolling has a significant effect on the transverse thickness variation of the finished cold-rolled strip. The urgency of the issue of edge drop increases due to the tendency to reduce the size of the side trim of steel strips, which directly affects the consumption coefficient, especially for expensive steel grades, which include transformer steel. To minimize the edge drop value, it is necessary to know the causes of its occurrence and rely on an adequate calculation of the shaping of hot-rolled strips. To create a predictive model of edge drop, rolling parameters are taken into account that affect the shape of the active generatrix of the work rolls. In the presented work, an analysis was made of the influence of hot rolling parameters on the edge drop of rolled strips of GO (transformer) steel. The revealed patterns will form the basis of the developed mathematical model.

Reprogrammable shape transformation of magnetic soft robots enabled by magnetothermal effect

Magnetic soft robots are promising for diverse applications, since they can achieve multimodal locomotion through programming magnetization. However, reprogrammable magnetization of soft robots remains a challenge. Here, we prepare a magnetic elastomer containing both Fe3O4 and CrO2 particles, where Fe3O4 nanoparticles can be heated through the magnetothermal effect. Once the temperature exceeds the Curie point of CrO2 particles, the original magnetization profiles of the elastomer can be erased and re-written. We tune the magnetization profile of a one-dimensional magnetic strip to realize three shape transformation modes, and the reprogrammed magnetization profiles are validated experimentally. The magnetothermal heating process is simulated. We also demonstrate reprogrammable shape transformation of two-dimensional magnetic soft structures. Finally, a reprogrammable hand-shaped soft robot is designed and used as a magnetic switch in a LED circuit.